Blitz the cookies, melted butter and salt in a food processor until they form a fine crumb.

Line a 9x9 pan with parchment paper.

Press down the cookie crumb using the back of a spoon or measuring cup, tightly packing it to form a crust.

Place in the freezer while you work on the remaining components.

Grind the chocolate cream cookies and set aside.

In a bowl, whisk the cream cheese with sugar and vanilla until it is creamy.

Add the heavy cream and whisk for a couple of minutes until the mixture is thick and holds shape.

Fold in the crushed cookies (you can taste and adjust the quantity).

Place the chopped chocolate or chocolate chips in a heatproof bowl.

Bring the cream to a boil, and pour over the chocolate.

Cover with a lid or plate for 5 min, then stir until a smooth, shiny ganache forms.

Remove the pan from the freezer.

Option 1 (for 4 layers): Spread on half of the cookies and cream mousse with an offset spatula. Pour over half of the ganache and spread it out. Place in the freezer for 10 min so the ganache can set. Repeat - first layer on the remaining cookies and cream mousse, then spread on the remaining ganache.

Option 2 (for 2 layers): Spread on the cookies and cream mousse with an offset spatula. Pour over the ganache and spread it out. Let the ganache set in the freezer before decorating.

Cover the cake and let it chill overnight in the fridge (at least 4 hours).

Whip up heavy cream with sugar until it forms medium peaks.

Spread the cream on top of the chilled cake, and sprinkle over crushed cookies.

Serve and enjoy!